Neurotoxins isolated from laboratory cultures of Gymnodinium breve, Florida's red tide, will be examined for neurotoxic mechanism of action utilizing an in vitro nerve-muscle preparation. Acute LD50 of the toxins will be determined in mice, utilizing oral, intravenous, and inhalation administration of the agents; and in chicks using oral and intravenous administration. Pharmacokinetic studies utilizing 14C-toxins will be used to determine the rate of translocation of the toxic agents into the blood-stream. Prolonged effects caused by chronic administration of the toxins will be examined by histopathology and serum enzyme assays following administration of the agents for 4 weeks. The potential effects of air-oxidized (no longer neurotoxic) toxins in the food chain will also be examined. The structures of the toxic compounds will be examined through chemical derivatization and spectroscopic analysis.